1. Field of the Invention
The present disclosure relates to a display device, and more particularly, to a display device in which defects resulting from attaching a functional panel to the display device are eliminated by removing bubbles generated in a transparent resin adhesive layer when a cover glass substrate is attached.
2. Background of the Invention
Flat panel display devices that are light, thin, short, and small are advantageous for use in various portable electronic devices such as mobile phones, personal digital assistants (PDAs), or notebook computers, and counterpart electronic devices. Liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), vacuum fluorescent displays (VFDs), and the like are different types of flat panel display devices.
Flat panel display devices are used in portable electronic devices such as mobile phones, tablet personal computers (PCs), and the like, and are used in display devices of large electronic devices such as TVs. In order to prevent damage to display devices from external impact, or the like, a hardened glass substrate is attached to a front surface of a display panel.
A cover glass substrate is attached by an adhesive formed of a transparent resin, or the like. However, when bubbles are present in a resin adhesive applied to attach the cover glass substrate to a display panel, adhesive strength between the display panel and the cover glass substrate is degraded and a path of light transmitted through the resin adhesive is changed, which causes a color shifting defect. In addition, the bubbles may include a foreign object, which may stain or scratch a screen of the display panel.
Also, in general, personal computers, portable communication devices, any other personally dedicated information processing devices, and the like, have a user interface controlled using various input devices such as a keyboard, a mouse, a touch screen, and the like. However, as portable electronic devices have developed, it is not practical to input information to portable electronic devices with input devices such as a keyboard, a mouse, and the like. Accordingly, display devices including a touch panel attached to a liquid crystal panel have been proposed to allow users to input information by directly contacting a screen with fingers, pens, or the like.
Also, display devices have been produced that provide holographic-type realistic three-dimensional (3D) stereoscopic images, allowing users to view, feel, and enjoy realistic and stereoscopic images rather than simple 2D images. Such stereoscopic image display devices include a parallax barrier or a 3D film patterned retarder (FPR) attached on a front surface of a display panel to separate images displayed on the display panel into a left-eye image and a right-eye image and to deliver different images to the left eye and to the right eye of users, thus displaying stereoscopic images.
In this manner, flat panel display panels include various functional panels such as a touch panel, a parallax barrier, a 3D FPR, or the like, attached to a front surface thereof so as to be used as display devices supporting various functions. Here, however, functional panels are attached to display panels through a transparent resin, or the like, causing a degradation of adhesive strength, color shifting due to a change in a light path, a defect due to a foreign object, and the like, like the case of attachment of a cover glass substrate.